DEPS: roll zlib: 20 new commits

DEPS

Index: DEPS
diff --git a/DEPS b/DEPS
index 4544c10a9524a488878549cc30eca5149dff862f..9a0c5cc40ba16e0646607130510cdd4a58e3a10f 100644
--- a/DEPS
+++ b/DEPS
@@ -17,7 +17,7 @@ deps = {
   # Slightly ahead of v 0.4.3, to include the fix for skbug.com/4038
   "third_party/externals/libwebp" : "https://chromium.googlesource.com/webm/libwebp.git@5ff0079ece626f122bfb8e33a5f92b5a68484176",
   "third_party/externals/nanomsg" : "https://skia.googlesource.com/third_party/nanomsg.git@0.4-beta",
-  "third_party/externals/zlib"    : "https://chromium.googlesource.com/chromium/src/third_party/zlib@4ba7cdd0e7bf49d671645264f839838fc56e1492",
+  "third_party/externals/zlib"    : "https://chromium.googlesource.com/chromium/src/third_party/zlib@c4e33043fb071b6ea0a153845da625d7ed633d3d",
   # NOTE: If we update libpng, we may need to update the generated file at third_party/libpng/pnglibconf.h
   "third_party/externals/libpng"  : "https://skia.googlesource.com/third_party/libpng.git@070a616b8275277e18ef8ee91e2ca23f7bdc67d5",
   "third_party/externals/giflib"  : "https://android.googlesource.com/platform/external/giflib.git@ab10e256df4f684260ca239905b1cec727181f6c",